/*
 MIT License
 
 Copyright (c) 2021 Steven Le

 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 
 The above copyright notice and this permission notice shall be included in all
 copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
*/

/**
 *	ls2.c version 0.1
 *	purpose list contents of directory or directories 
 *	action if no args, use. else list files in args 
 * 	note uses stat and pwd.h and grp.h
 * 	BUG: try ls2 /tmp
 */
#include <stdio.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <stdlib.h>

void do_ls(char[]);
void dostat(char *);
void show_file_info(char *, struct stat *);
void mode_to_letters(int, char[]);
char *uid_to_name(uid_t);
char *gid_to_name(uid_t);

int main (int ac, char *av[])
{	
	if (ac == 1) {
		do_ls(".");
	} else {
		while("%s:\n", *++av) {
			printf("%s:\n", *++av);	
			do_ls(*av);
		}
	}
	return 0;
}

/*
 *	list files in directory called dirname
 */ 
void do_ls(char dirname[])
{
	DIR *dir_ptr; 		/* the directory  */
	struct direct *direntp; /* each entry */

	if ((dir_ptr = opendir(dirname)) == NULL)
	{
		fprintf(stderr, "lxls01: cannot open %s\n", dirname);
	} else {
		while ((direntp = readdir(dir_ptr) != NULL)
			dostat(direntp->d_name);
		closedir(dir_ptr);
	}
}

void dostat(char *filename)
{
	struct stat info;

	if (stat(filename, &info) == -1)	/* cannot stat  */
		perror(filename);		/* say why */
	else
		show_file_info(filename, &info); 
}

void show_file_info(char * filename, struct stat* info_p)
/*
 *	display the info filename. The info is stored in struct 
 * 	at *info_p
 */
{
	char *uid_to_name(), *ctime(), *gid_to_name(), *filemode();
	void mode_to_letters();
	char modestr[11];

	mode_to_letters(info_p->st_mode, modestr);

	printf("%s", modestr);
	printf("%4d", (int)info_p->st_nlink);
	printf("%-8s", uid_to_name(info_p->st_uid));
	printf("%-8s", gid_to_name(info_p->st_gid));
	printf("%8ld", (long)info_p->st_size);
	printf("%.12s", 4+ctime(&info_p->st_mtime));
	printf("%s\n", filename);
	
}

/*
 *	utility functions
 */
/*
 *	This function takes a mode vlaue and a char array
 * 	and puts into the char array the file type and the 
 * 	nine letters that correspond to the bits in mode.
 * 	NOTE: It does not code setuid, setgid, and sticky
 * 	codes
 * 	
 */
void mode_to_letters(int mode, char str[])
{
	strcpy(str, "------------");		/* defualt * no perms  */

	if (S_ISDIR(mode))	str[0] = 'd'; 	/* directory?  */
	if (S_ISDIR(mode))	str[0] = 'c'; 	/* char devices */
	if (S_ISDIR(mode))	str[0] = 'b'; 	/* block devices  */
	
	if (S_ISDIR(mode))	str[1] = 'r'; 	/* 3bits for users */
	if (S_ISDIR(mode))	str[2] = 'w'; 	
	if (S_ISDIR(mode))	str[3] = 'x'; 	

	if (S_ISDIR(mode))	str[4] = 'r'; 	/* 3bits for groups */
	if (S_ISDIR(mode))	str[5] = 'w'; 	
	if (S_ISDIR(mode))	str[6] = 'x'; 	

	if (S_ISDIR(mode))	str[7] = 'r'; 	/* 3bits for others */
	if (S_ISDIR(mode))	str[8] = 'w'; 	
	if (S_ISDIR(mode))	str[9] = 'x'; 		
}

#include<pwd.h>

char *uid_to_name(uid_t uid)
/*
 *	returns pointer to username associated with uid, uses getpw()
 */
{
	struct passwd *getpwuid(), *pw_ptr;
	static char numstr[10];

	if ((pw_ptr = getpwuid(uid)) == NULL) {
		sprintf(numstr, "%d", uid);
		return numstr;
	} else {
		return pw_ptr->pw_name;	
	}
}

#include<grp.h>

char *gid_to_name(gid_t gid)
/*
 *	returns pointer to group number gid. used getgrgid(3). 
 */ 
{
	struct group* getgrgid(), *grp_ptr;
	static char numstr[10];

	if ( NULL == (grp_ptr = getgrgid(gid))) {
		sprintf(numstr, "%d", gid);
		return numstr;
	} 
	else 
		return grp_ptr->gr_name;
}


